1. Field of the Invention
This invention is directed to an adaptive activation control unit for an occupant restraint system of a vehicle. This control unit was designed specifically for use with the two major kinds of restrain systems; namely, seat belts and air bags. In a collision, both the pre-tensioner devices of seat belts and air bags have to be activated in time so that the driver and a passenger can be well protected.
2. Prior Art
In the past, the main activation control system was composed of several impact sensors installed in different parts of an automobile: the activation is determined by the deceleration magnitude received by these sensors. Though the system may be reliable, it still has the following problems or disadvantages:
(1) These sensors are usually installed at the "crash zones" of an automobile. After a collision takes place, they usually need to be replaced, which is not cost effective. PA0 (2) The central control device has to be connected to the sensors by a wire harness; so, the reliability of the system is decreased. In addition, these wires may be damaged by the collision that the system is designed to detect, which may cause a failure of the activation control. PA0 (3) A certain type of sensor may be specifically designed for a certain type of automobile; different sensors may have different activation criteria. Also, those impact sensors are more expensive to be adjusted or fixed, and are not cost effective as a result. PA0 (4) In a collision, because the driver and passenger are located in the non-crash zone of the automobile, the impact condition imposed on these people will be different from that on the sensors. Therefore, this impact magnitude different may cause an unnecessary activation of the air bag or other protection device. PA0 (5) These systems have a weaker self-testing capability.